The present disclosure relates to a high voltage direct current (HVDC) valve tower.
A HVDC transmission system is to convert high-voltage AC power produced from a power plant into DC power using an electric power converter, transmit the converted DC power, convert again the DC power into the AC power and then supply the converted AC power.
The HVDC transmission system has some advantages in that it has a low power loss, an insulation work is easy due to its lower voltage compared to the AC power, and a power transmission tower may have a reduced size and height due to its low induced lesion. Further, it is possible to connect two AC systems having different voltages or frequencies and thus to improve stability of the AC systems, and also when an AC system breaks down, it is possible to prevent the breakdown from being spread to other adjacent systems. Therefore, the HVDC transmission system is used as a power system connecting means of new renewable energy, particularly used for power transmission in a large-scale offshore wind generation farm, or the like.
An AC/DC converting device for converting an alternating current into a direct current is provided at a HVDC substation in which the AC power is converted into the DC power.
The AC/DC converting device is also called as a valve module (hereinafter, referred to as the “valve module”). In a current source HVDC system, a thyristor valve is used for the AC/DC converting device, and in a voltage source HVDC system, an IGBT device is used for the AC/DC converting device.
In the HVDC system, the plurality of valve modules are vertically stacked according to a power transfer capability and constitutes a valve tower.
As illustrated in FIG. 1, the valve tower may be fixed to an inner ceiling of the substation in order to protect the valve modules from environmental risk factors such as earthquake.
FIG. 1 is a schematic view illustrating a general valve tower. Referring to FIG. 1, the plurality of valve modules are stacked on and connected with each other through supporting insulators 20 and thus constitutes the valve tower.
The valve modules 10 may be disassembled from the valve tower in order to have a periodic inspection or repair a trouble. However, since the plurality of valve modules 10 are connected in series, a part or the whole of the valve modules 10 should be disassembled from the valve tower in order to separate a specific valve module 10. That is, when separating the uppermost valve module 10, it is necessary to disassemble the valve modules 10, in turn, from the lowermost one. Therefore, the whole of the valve modules 10 should be disassembled in order to separate the specific valve module 10.
FIG. 2 is a schematic view illustrating another general valve tower. Referring to FIG. 2, the plurality of valve modules 10 are stacked on and connected with each other through supporting insulators 20 and thus constitutes the valve tower.
In this case, in order to separate the valve module 10 from the valve tower, a hoist which is moved along a rail installed on the ceiling should be moved to a predetermined position, and then the valve module 10 is separated by an operation of the hoist.
However, since the plurality of valve towers are generally installed over a comparatively wide area, the rail for moving the hoist should be also installed over the whole ceiling, and thus the cost of equipment is increased. Further, since it is necessary to move the hoist at the predetermined position and then perform the operation of the hoist, it takes a long period of working time.